vec4 marschnerLobb(VOLUME_STRUCT volumeStruct, vec3 samplePos) {
	const float PI = 3.1415926535;

	// some adjustment
	vec3 t = texToWorld(samplePos, volumeStruct);
	t = (t*(1.0-volumeStruct.datasetDimensionsRCP_) + vec3(0.5)*volumeStruct.datasetDimensionsRCP_);
	t.xy *= 1.6;

	return vec4(0, 0, 0, 0.4 * (0.25 * (cos(12 * PI * cos(sqrt(t.x * t.x + t.y * t.y))) + 1) - sin((PI * t.z)/2) + 1));
}